1. Field of the Invention
The present invention relates generally to inert gas welding. More particularly, the invention is directed to purge dam constructions for retaining purge gas around a weld zone.
2. Description of Prior Art
When welding together pipes and other enclosed structures using inert gas welding, it is desirable to purge the interior of the pipe or structure in the vicinity of the weld zone to prevent corrosion and the formation of oxides on the interior side of the weld pool. Purge dams are conventionally used for this purpose. For example, when welding the ends of two pipe sections to form a consolidated pipe run, two purge dams are placed in the pipes, one in each pipe on either side of the weld zone. A purge gas can then be introduced into the area between the dams, usually by way of a needle injector inserted through a gap in the pipe end interface to be welded, to drive off the atmospheric contaminants. The present application is directed to improvements in purge dam construction.